Noninvasive investigation for renal artery stenosis: Contrast-enhanced magnetic resonance angiography and color Doppler sonography as compared to digital subtraction angiography

Introduction: The question about the most appropriate non-invasive method f or detecting a renal artery stenosis (RAS) when comparing contrast enhanced magnetic resonance angiography (MRA) and color Doppler sonography (CDS) is still under discussion. Therefore we conducted a prospective study in orde r to evaluate both methods as compared to digital subtraction angiography ( DSA). Patients/Methods: Thirtysix consecutive patients (53,9 +/- 13,7 years) with suspected RAS were investigated. MRA was performed using gadolinium for co ntrast enhancement. CDS was performed using a 2.5 and 3,5 MHz transducer. A peak systolic velocity (Vmax) > 200 cm/sec within renal arteries and/or a side to side difference of the resistive index (RI) of >0,05 were used to d iscriminate stenosis. A diameter reduction of greater than or equal to 60% by DSA was considered a stenosis relevant to the patient. Results: Sixtyeight main renal arteries and 9 accessory vessels were detect ed by DSA. Twenty main and 3 accessory arteries were found to be stenosed g reater than or equal to 60%, while 4 main and I accessory artery presented with occlusion. MRA detected 70 renal vessels (65 main and 5 accessory arte ries). Twentyone stenosed arteries and 4 occluded vessels were correctly di agnosed by MRA. With CDS 68 renal vessels (62 main and 6 accessory arteries ) could be visualized out of which 21 stenoses were diagnosed because or in creased Vmax and 6 stenoses were detected because of a side to side differe nce of RI. For main renal arteries sensitivities and specificities were 96% and 86% for MRA and 96% and 89% for CDS. Conclusions: MRA and CDS are both comparable methods for detection of a ren al artery stenosis greater than or equal to 60%. Despite several limitation s, CDS can at the moment still be favored as a screening method.